The invention relates to apparatus for heating of liquids and more particularly to such apparatus designed for the use of solid fuels such as wood, coal, peat, hay or other chunk fuels.
Many devices have been proposed for deriving heat from the burning of solid-type fuels and for using the thermal energy derived from such combustion to heat room spaces, liquids, or other elements. Wood burning stoves, for example, have been equipped with liquid-containing coils or tanks in order to utilize the stove heat for the further heating of water for domestic use.
In some of these prior cases, the heating of liquid is merely an auxiliary function of a wood or coal burning unit which is primarily intended for other uses, such as cooking. In other cases, the solid-fuel-burning unit has been incorporated in a boiler to heat liquid under pressure for the generation of steam or for transmission of such heated liquid to other locations for storage or immediate use.
Pressurized boilers or tanks must meet minimum code standards requiring such safety devices as pressure relief valves. The fireboxes of such solid-fuel-burning units also reach such temperatures that special insulation must be provided, or the units must be isolated from wooden or inflammable structures such as buildings, with construction code limitations as to the necessary spacing of the heated portions of such units from the walls or other portions of any building in which such a unit is located or any structures adjacent to such units.